This is a sexual act that begins by positioning a chick with has her ass straight up in the air with only the back of her head and neck touching the floor. She can be held in position by a couch or small table. A more flexible & talented ho can use the back of her arms and elbows to get her ass in the right position.
A dude then stands over the chick, spits on her pussy, aims his cock straight down with his right hand, and drives it with much force into her cunt. Then the cock is completely pulled out and the process is repeated.
I gave her the Portland Piledriver on the first date and the bitch did not bat an eye. What a ho.